Polymeric strain gauges have been proposed.
WO 96 19758 discloses the preparation of pressure sensitive ink that can be used for the fabrication of pressure transducers such as strain gauges where the electrical resistance is indicative of the applied pressure. The ink has a composition of an elastic polymer and semiconductive nanoparticles uniformly dispersed in this polymer binder.
U.S. Pat. No. 55,817,944 discloses a strain sensor for a concrete structure containing conductive fibres.
U.S. Pat. No. 6,079,277 discloses a strain or stress sensor composed of a polymeric composite with a matrix of carbon filaments.
U.S. Pat. No. 6,276,214 discloses a strain sensor using a conductive particle—polymer complex. Carbon black is dispersed in an ethylene vinylacetate copolymer to produce a conductive polymeric matrix.
All these polymeric sensors are fabricated by preparing the conductive particles and then incorporating them in a polymer by solution or melt processing followed by film fabrication. This component is then pasted onto an insulating support and embedded onto the mechanical structure to be monitored. Electrical leads need to be connected to the sensor. Polymeric strain gauges relying on changes in resistance of a conducting film are usually unsatisfactory and do not have a long service life due to hysteresis. Generally metallic strain gauges are preferred.
WO 0223962 discloses a laser irradiation process for forming conducting patterns on an insulating substrate.
JP 2000216521 discloses patterning of circuits for printed circuit boards by laser irradiation.
U.S. Pat. No. 5,900,443 deals with near surface treatment process produced by irradiation with high-energy particle beams. The process is preferably implemented with pulsed ion beams. The process alters the chemical and mechanical properties of the polymer surface. The ion beam radiation can have various effects such as cross-linking, pyrolysing, etching or ablation of the polymer in the treated areas. However there is no mention of conductivity in the polymer. It is an object of this invention to develop a process with fewer fabrication steps to form easily mass produced strain sensors.